Carnival Corp. said today that its longtime CEO Micky Arison will step down after a series of ship mishaps that have prompted the largest cruise ship operator to offer steep discounts.

Arison, who has been CEO since 1979, is being replaced by Arnold W. Donald, who has been a director for 12 years. Arison will continue to serve as chairman of the board, Miami-based Carrnival said in a statement today.

Second-quarter profit rose to 5 cents per share, up from 2 cents a year ago. But revenue fell 1.7 percent to $3.48 billion.

Several of the line's cruise ships have experienced power losses in the past two years and its Costa Concordia ran aground in 2011, killing 30 people.

"I have been discussing this with the board for some time now and feel the timing is right to align our company with corporate governance best practices," Arison said in the statement. The company is splitting its chairman and CEO roles, which were both held by Arison.

Two months ago, Carnival announced improvements that would upgrade safety and create redundant power systems on its entire fleet.

Added to a previously announced program, the line will put between $600 million and $700 million into improving its ships to avoid incidents like the one that occurred on its Carnival Triumph in February.

Carnival operates 10 brands including Princess and Cunard.

The systemwide improvements outlined included:
An increase in emergency generator power across Carnival Cruise Lines' fleet of 24 ships and additional investments in the newest and most technically advanced fire prevention, detection and suppression systems. All of Carnival Cruise Lines ships will have two separate, redundant engine rooms.